Page 64 - Handbook of Adhesion Promoters

4.1 Surface evaluation 57

Figure 4.4. Field-emission scanning electron microscopic images of the samples prepared with different cleaning
procedures: (a) degreasing, (b and b ) alkaline etching at different magnifications and (c and c ) alkaline etch-
2
2
1
1
ing followed by acid cleaning at different magnifications. [Adapted, by permission, from Gohru, SS; Attar, MM;
Ramezanzadeh, B, Prog. Org. Coat., 87, 52-60, 2015.]
2+
6
layer strongly increased the adhesion due to the presence of Zn ions. Bacteria were
o 6
found to have a hydrophilic surface with a water contact angle of 23.5 .
These observations show us that the condition of the surface (the most frequently
unknown and not sufficiently analyzed in most research) has a profound effect on adhe-
sive properties. This leads to the following conclusions:
• if results of adhesion studies cannot be fully understood and explained, surface of
adherent has to be studied in more detail because its condition may hold a key to
recognition of missing variables